Method of abrading



June 3, 1952 E. L. DRYER METHOD OF ABRADING Filed June 50, 1948 EDWARD L. DRYER 4, M 4-( Patented June 3, 1952 METHOD OF ABRADIN G Edward L. Dryer, Lancaster, Pa., assignor to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania Application June 30, 1948, Serial No. 36,013

Y Claims. 1

This invention relates to a method and pparatus for abrading and is concerned particularly with the abrading of cork composition and similar materials containing an ingredient of a thermoplastic nature which tends to load the grinding wheel.

In the manufacture of cork composition disks for lining closures such as crowns, the binder for the cork composition includes a lubricant such as a mixture of paraffin wax and synthetic rubber latex. This material tends to migrate somewhat to the outer surface of the rod during heating in the course of manufacture and thus makes it possible to easily remove the rods from the forming molds. In rods manufactured by the extrusion process, the extrusion or forming tube would be the mold surface which must be lubricated continuously in order to permit proper formation of the extruded rod.

The cork disks must be of a substantially uniform diameter, and, consequently, th outer surface which is somewhat rough and. irregular is generally severed. According to my invention, a centerless grinding machine is rendered useful for this purpose. In attempts to employ centerless grinding on cork composition rods heretofore, indifferent success was achieved, and it was found that frequent wheel dressings were necessary in order to maintain a reasonably close tolerance in the finished diameter of the rod; In the grinding operation, it was found that the thermoplastic lubricant, particularly rich at the surface of the rod,'tended' to fill the grinding wheel or load it, as the trade terms it. In centerless grinding, the finished diameter of the workpiece is predetermined by the spacing between the abrading surface of the grinding Wheel and the working surface of the regulating wheel between which the workpiece is fed. Any loading of the grinding wheel, therefore, decreases the distance between the abrading surface and the regulating surface, and the finished diameter of the workpiece is reduced. In addition, the loading of the wheel tends to decrease the abrasive action, and the speed of cutting and the smoothness of out are impaired.

It is an object of my invention to provide a method whereby the working surface of the abrading wheel may be continuously cleaned to remove thermoplastic material deposited therein.

Another object of my invention is to provide a method of centerless grinding cork composition elements or the like wherein the grinding wheel is heated to melt a thermoplastic ingredient deposited therein during the grinding operation and application of my invention to a centerless grinding wheel; and

Figure 3 is a view similar to Figure 2 illustrating a regulator wheel cleaning arrangement.

Referring to Figure 1, the centerless grinding machine as a whole has been indicated by the numeral 2. It includes a power driven grinding wheel 3 and a driven regulating wheel 4. A work support 5 is disposed between the wheels 3 and 4 and supports the workpiece B in an abrading zone. These elements are conventional in centerless grinding machines, and a description of the mechanism for rotating the wheels and adjusting their positions is'not deemed necessary.

It will be assumed, for purposes of illustration, that the workpiece 6 is a cork composition rod which is to be reduced to a desired diameter and subsequently severed into disks in the fabrication of crown closures The cork composition material has been formed by an extrusion process and is made up of relatively fine cork granules bound together with a binder composed. of glue and glycerine and having a' mold lubricant incorporated therein and formed of a mixture of synthetic rubber latex and parafiin w'ax. The lubricant has migrated to the surface of the rod and is, therefore, rich at such surface;

As previously mentioned, in centerless grinding the diameter of the workpiece 6 'will be determined by the distance between the working face of the grinding wheel 3 and the regulating surface of the wheel 4, as will be evident from an examination of Figure 1. Thus, any tendencyfor the grinding wheel 3 to increase in diameter by the building up of material abraded from the ele-. ment 6 will result in a diminution ofthe finished diameter of the workpieceli. The same is true of any building'u on the regulating surface 4, although this is not as great because the surface 4 is not an abrading surface. t

In the abrading operation on a cork composition including a thermoplastic binder and'a thermoplastic lubricant, there is an excessive tendency for the grinding wheel 3 to load.- Common practice has been to grind a few rods and i m tion d. I have fo nd it poss ble to s n hundreds of cor r ds/pr or to any equ remen for re i o the Whee The. te m has. been found efiective for heating the abrading sure .then dress the'wheel 3 to present a fresh abrading surface free of loading and then adjust the wheel 4 to provide the desired spacing to give a finished diameter to the workpiece within the tolerances allowable.

According to my invention, I provide a con duit for steam under pressure which conduit is indicated ,at- I in the drawing." ''This conduit, ex:

Ltends across the working face of the wheel 3 and is provided with a plurality of openings 8 which are positioned so as to direct the steam under pressureagainst' the working face of the grind: 'ing wheel. lpositioned closely adjacent the. working face of thegrinding wheel at aposition in advance of Ithe abrading zone along the direction of travel .of the g rinding wheel; as will be noted frgm I Figure 1 where an arrow indicates the dirctioii'of travel ofthe grinding wheel, In actual practice The conduit 1 with the Openings" 815 using a grinding wheel 20 inches in diameter hav- 1 ns; tr rchiace. and. ferri d of Ne 69 exit I.: have videe a double row oihclee 8 he ho es he; fing inch in diameter and spaced? /8 1149 91.1

nte e' it t two'rows being s aced /8. inch apart a d t e h l s in ad acen ows bein sta e er i hav u e steam unde 19 ound i u e- Withia c rk composit oho h pe de-. s ibed above a d ntaining the. mo hibri fa s itlceves the brading z ne. and this at is eii f h t e-me t t e. thermo last c f e eciieht n se es to f ush them e aysfrom hc d ne. urf ce Ae he wh el continues roie i from the zone of steam application,

he surface s c led; and. at. the time the a y te d nc r he r nd n w ee to load up.

hated,

he's indcr at a at of 0 teet per minute.

compgisition' element containing a thermoplastic' i'ngrdientthe'steps comprising rotating an abrading surface in engagement with said cork composition element at an abrading zone in which said thermoplastic ingredient is imbedded in said abrading surface,fheatingthe abrading surface as itleaves the abradin zone by directing steam under pressure against said surface to melt said thermoplastic ingredient and remove the same out of said abrading surface, and'there I after cooling said surface to a temperature below the melting point of said thermoplastic ingredientprior to 're-entrance of the heated, cleaned,

and cooledabrading surface into the abrading.

zone,

3. In a'method of centerless grinding a cork composition element containing a thermoplastic waxy material the steps. comprising rotating an I I abrading surface in engagement with said cork w eel ire-en er ee oredins zone, the heated and. cleane s r has been cooled o a no. .,t t here g i di th y be e fe ted effici ntly.- Thus, a

th the ma e i ev re from he surface of t cork om c it workpiece is e11... and, consequ a h spaced elati nship be.- w e he e e i e- Su f e nd the. e ulati :surface is maintained; I; have found that it is poss ble o. ntai the nished d ameter-Qt '3 k om os i n r d 1 1-935 n h within .015 of a nch o e a per od o e e hundre rindl es ct workp e s i8. inch on f through There is. som tr sf r o evered cork ranules] and binder to the regulating surface Q i the wheel 3 end in der t maintain t s wheel c ear I i gide a doctor b ade 8 whi h is maintained in engagement with the regulating Surface. The

blade is. effective for removing any slight amount of" abraded material which may be transferred a from the'workpiece to that surf-ace.

M e my inv n n is articularly useful in. e ri in of co c .moos o re s u ed in j the manufacture. of closure liner d sks. it is 1 q l ap li able t the gri n o ollow cork composition cylinders used in the manufacture of-. cork"compositionltextile cots. It will also. be j found useful in'the centerless grinding of other materials, containing. a thermoplastic ingredient crihsr'eld ei t .which ay b me ted nd f us ed out oflthe abrading surface,

Whi I have illustrated nd d scribe a rerredembodiment' limy in e n it wi l be I understood that thefsame is, not; limited thereto 1 but may be. otherwise embodied and practiced 1 thi the. scope. of he. fo owine c a ma composition element at an abrading zone in 1- 'which zone said waxy material becomes 'imbed- (led in said abrading surfaca'heating the abrad-.

ing. surface as it leaves the abrading zone to a temperature above the melting point of said waxy material by directing steam under pressure against said surface. and melting said'thermoplastic waxy material and removing the same from the abrading Surface, and thereafter cooling said surface to a temperature below the melting point of said waxy material prior to re-' entrance of the heated, cleaned, and cooled abrading surface into theyabradingzone.

e 4. In a methodof centerless grinding a cork composition element containing a thermoplastic ingredient the steps comprising rotating an abrading; surface, and. a regulating surface in n a ement with said cork: composition element at an abrading Zone in which zone said thermoplastic. ingredient is imbedded in said abrading surface and a portion thereof is transferred to d. regu ati surface, heating the abrading -lace as: i leaves the abrading zone by directfin s eam. a a nst said surface to melt said" thermoplas c.in redient; said steam b in pplied undenpressure sufficient to flush the melted thermoplastic ingredient out of said abrading rface. an ma ntainin -predeternuned space relationshipbetween said abrading surface and said regulating surface by removing from said regulating surface thermoplastic material transfer ed theret 1 5. In a method of centerless grinding acork composition element containing a thermoplastic ingredient the steps, comprising continuously rotating an abrading surface in engagement with said c; o composi ion e ement at an abrading zone, continuously rgtating a. regulating surface in engagement with said cork composition ele-. mentatfsaid abrading zone continuously heating the abrading surface as it leaves the abrading zone by directing steam under pressure against said surface to melt said thermoplastic ingredient, said steam being applied under sufficient pressure to flush out the melted thermoplastic ingredient from the abrading surface, continuously removing transferred portions of said cork composition element from said regulating surface to thereby maintain a predetermined spaced relationship between said abrading surface and said regulating surface, and continuously cooling said abrading surface to a temperature below the melting point of said thermoplastic ingredient prior to entrance of said abrading surface into the abrading zone.

EDWARD L. DRYER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 523,046 Lowman July 17, 1894 967,798 Lowman Aug. 16, 1910 1,413,060 Roberts Apr. 18, 1922 1,733,092 Einstein Oct. 22, 1929 1,772,042 Heim Aug. 5, 1930 1,910,748 Burk May 23, 1933 2,033,335 Haas et al. Mar. 10, 1936 FOREIGN PATENTS Number Country Date 701,220 Germany Jan. 11, 1941 

